1. Field of the Invention
This invention relates to machines which lay out spaced assemblies of textile yarns or similar fiber structures. The general field would include conventional looms and knitting machines along with more specialized equipment such as that described in U.S. Pat. No. 4,249,981 to Pelletier. However, unlike the vast majority of such machines, this invention relates to laying out yarn arrays which are eventually incorporated into a continuous web in which the yarns are neither parallel nor perpendicular to the edges of the web but inclined at an angle thereto between ten and eighty degrees. This invention is particularly adapted to laying out yarns which are kept substantially straight and are not woven, knitted, sewn, or otherwise regularly distorted from a straight path, except to the extent necessary at the edges of the web to form a selvage or similar structure.
This invention is most particularly adapted for laying out straight laid narrowly multidirectional yarn arrays such as are disclosed in an application for United States Patent entitled "Improved Joining Tape and Process Therefor" by applicants Dhiraj H. Darjee and Daniel E. Devine, filed on the same date as this application and assigned to the same assignee as this application under Ser. No. 672,988.
As outlined in more detail in said application by Darjee and Devine, hereinafter cited simply as Darjee, a common requirement of industry and commerce is to convert a material manufactured in continuous web form into an endless belt. One of the most common methods for accomplishing this purpose is called a butt joint. A reinforcing material, variously called a tape, patch material, etc. is usually added to one side of the butt joint to strengthen it.
The particular type of tape described by Darjee is used primarily for joining coated abrasive products into endless belts. Such joints are normally made at an angle other than perpendicular to the edge of the belt. The Darjee tape is reinforced with yarns for increased tensile strength, and it is naturally advantageous for these reinforcing yarns to be oriented in or near to the running direction of the belts made with it. For reasons detailed by Darjee, the most practical method of achieving this goal is to lay out the yarn array during the manufacture of the tape with the yarns at an angle to the edge of the layout. In order to avoid a tendency of the patch material to split under certain types of stress, the yarns are not laid out strictly parallel to one another, but instead in two groups. Yarns within each group are parallel, but the two groups cross each other at a small angle up to 5.degree..
2. Description of the Prior Art
Triaxial weaving machines, which lay out two groups of yarns corresponding to the fill of a conventional fabric at both sixty degree angles to the warp yarns, are known but are believed to be little used. Knitting and stitch-bonding machines which can lay out yarns in angled patterns are also known. However, all these machines are designed primarily for making fabrics and thus normally require that at least some of the yarns used be interlaced, knitted, or otherwise repeatedly diverted from a straight path. The Pelletier machine already noted lays out what are called "weft webs" in which the yarns are straight, but it is adapted only to laying out such webs with the yarns perpendicular to the edges of the webs. We are not aware of any prior art machine efficiently adapted to laying out biased webs of straight laid yarns at variable angles to the edge of the webs.